Nutritional studies have indicated that some of the essential amino acid threonine in various plant proteins including soybeans is biologically unavailable. This becomes a nutritional problem for people subsisting on marginal diets deficient in protein or composed primarily of plant protein. The reason for the poor availability of threonine is not clear. Little is known about the structure of most of these plant proteins other than their amino acid content. This research is designed to elucidate those structural features of soybean proteins which could influence the availability of threonine by preventing its release by digestive enzymes. The structural studies are directed to identification of the bonding and amino acid sequence and the carbohydrate structure of the carbohydrate-protein core of the soy glycoproteins. Research procedures involve characterization of the glycopeptide and other threonine fragments and a study of rates of digestion of the glycoprotein by pancreatic and intestinal mucosal enzymes to identify resistant peptide bonds.